You're right, it is in the new beta, hockeykid informed me about this just last night. I wasn't aware that it had been worked on.
However, a few things he mentioned to me relating to it, though, are disappointing at this point in time. Namely, scripted flak is not explodable (FAIL), and it has no collision (EPIC FAIL)
Not trying to make anyone look bad or anything, but keep in mind that this feature is still progressing and isn't finished. Hockeykid mentioned that Lee was working on this feature himself, so I've no doubt he already knows these discrepencies need fixing and will sort it out in the end.
The one and only,